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Biomedical subjects

A Hoffmann

Publications and source records attributed to A Hoffmann.

At least 433 records · Page 24Linked to original sources
PubMed1983

Influence of thrombin inhibitors on the thrombin-induced activation of human blood platelets.

The influence of thrombin inhibitors, which differ both in their chemical structure and type of inhibition, on the thrombin-platelet reaction was studied. The inhibitory effects of the competitive inhibitors tested on the thrombin-induced platelet reaction correlated well with their effects on the thrombin-catalyzed fibrinogen conversion and on the thrombin-catalyzed hydrolysis of synthetic substrates. Heparin and antithrombin III inhibited the thrombin-induced platelet reaction. However, heparin did not potentiate the inhibition by antithrombin III of the thrombin-platelet reaction.

Antithrombin III↗
PubMed1982

[Inhibition and triggering of heart pacemakers by muscle potentials].

The unipolar pulse generator systems were tested in 220 patients (96 VVIM, 97 VVIO, 27 physiological systems) to determine the incidence of sensing interference with muscle potentials. 23% exhibited oversensing, with a sex distribution of 32% for males and 15% for females. The interference was observed more often in VVIM pacemakers at nominal setting (35%) than in VVIO pacemakers (11%). In DDD pacemakers both inhibition and triggering of ventricular stimulation was observed. Among the 23 patients with persisting syncope or dizziness after implantation of the pacemaker, the symptoms were observed during physical activity only in 5. In these 5 the underlying arrhythmia was tachycardia in 3 and inhibition of the pacemaker by muscle potentials in only one patient.

Action Potentials↗
PubMed1982

[Non-invasive evaluation of pressure gradients in aortic stenosis using Doppler ultrasound].

In 35 consecutive patients with aortic stenosis, noninvasive assessment of pressure gradients was performed using a continuous wave Doppler ultrasound technique prior to left heart catheterization. Maximum blood flow velocity in the ascending aorta and time from aortic valve opening to peak velocity in relation to left ventricular ejection time (TPV) were measured. Doppler data proved reliable in predicting a pressure gradient above or below 50 mm Hg (sensitivity 89% and specificity 88%). Pressure gradients calculated from the frequency shift of the ultrasound wave correlated well with pressure measurements obtained at cardiac catheterization in 31 patients with adequate Doppler velocity signals (r = 0.85, p less than 0.001). In all 4 patients with inadequate velocity signals a pressure gradient above 50 mm Hg could still be predicted by an abnormally delayed timing of peak velocity in systole (TPV greater than 0.5).

Adolescent↗
PubMed1982

[Non-invasive determination of pressure gradients of heart valve prostheses using Doppler ultrasound].

Noninvasive measurements of pressure gradients by continuous wave Doppler ultrasound technique were carried out in 40 patients with correctly functioning heart valve prostheses (10 Björk-Shiley in aortic position, 10 Björk-Shiley in mitral, 10 St. Jude Medical in aortic and 10 St. Jude Medical in mitral) and in 10 patients with normal aortic and 10 patients with normal mitral valves. The pressure gradients were slightly but significantly higher in prosthetic than in normal heart valves (p less than 0.005). Pressure gradients in Björk-Shiley prostheses were higher than in St. Jude Medical prostheses both in aortic (18.4 +/- 2.6 vs 9.6 +/- 1.9; p less than 0.01) and in mitral position (8.2 +/- 1.1 vs 5.4 +/- 0.8; p less than 0.05). The pressure gradient was inversely related to valve size in Björk-Shiley prostheses (r = -0.60 for aortic and r = -0.42 for mitral valves; p less than 0.05) but not in St. Jude Medical prostheses. The non-invasive Doppler technique should be useful in the diagnosis of prosthetic valve obstruction.

Aortic Valve↗
PubMed1982

Cardiovascular reflexes in conscious toads.

Methods used for implanting sensors and catheters in temporarily ether-anesthetized toads (Bufo paracnemis) are described. Following recovery it was found that distension of the pulmocutaneous arterial trunk and high frequency electrical stimulation of the laryngeal nerve of conscious toads induce an abrupt fall in arterial pressure accompanied or not by bradycardia or cardiac arrest. A brief suppression of throat movements may occur but this is not a constant finding. The response is blocked by atropine or methyl-homatropine and persists in animals with high spinal sectioning, thus indicating its cholinergic parasympathetic nature. However a certain amount of sympathetic inhibition is not ruled out. Perfusion of the artery with lobeline and electrical stimulation of the laryngeal nerve at low frequency (1/s) induces a rise in arterial pressure which is blocked by phentolamine. The hypertension is followed by enhancing of both throat oscillations and electromyographic discharges. The occurrence of chemoreceptors in the pulmocutaneous arterial wall in these animals is discussed. Blockage of the laryngeal nerve with lidocaine or perfusion of the pulmocutaneous arterial trunk with the same solution elicited a blood pressure rise, tachycardia and enhanced ventilatory movements. This was attributed to suppression of the baroreceptor tonus.

Animals↗
PubMed1982

Influence of benzamidine derivatives on thrombin-induced platelet reactions.

The influence of competitive synthetic thrombin inhibitors of the benzamidine type on the thrombin-platelet reaction was studied. The benzamidine derivatives tested inhibited thrombin-induced aggregation and 5-HT release in dependence upon their affinity for the enzyme. Accumulation of platelets in the lung of rats and the fall in platelet counts in the blood of rabbits induced by thrombin infusion were prevented by infusion of the inhibitors, as illustrated by example of 3-TAPAP. The thrombin-platelet reaction was inhibited at higher doses of inhibitor than those required for inhibition of coagulation. In this way, the inhibitors may exert a different influence on the various haemostatic steps.

Amidines↗
PubMed1981

[Incidence and nature of thoracic pains in outpatients (author's transl)].

The incidence of different types of thoracic pain in outpatients at the Medical University Policlinic, Basel, was obtained for comparison from a random sample of the Swiss population. The data from the Rose questionnaire which was used were compared with the case histories. Of 515 patients, 233 admitted having thoracic pains. These complaints were the reason for consulting the doctor in 71 patients. Of all patients who admitted thoracic pains, 14% complained of typical ischemic pains and 60% of unspecific thoracic pains. Perusal of the case histories showed that the doctor was only able to distinguish between coronary heart disease, other organic causes and functional complaints after selective history taking and clinical examination in 89% angina pectoris and 74% unspecific thoracic pains.

Adolescent↗
PubMed1981

[Epidemiology of blood pressure in 4 Swiss cities].

Within the framework of the Swiss National Research Program for the Prevention of Cardiovascular Disease, blood pressure levels of 8140 adults were recorded in four Swiss cities. Repeated measurements yield lower results. The values increase with age and are higher in men than in women. Swiss citizens have higher mean values than foreigners, and values in the French-speaking cities are significantly higher than those of the German-speaking cities. The prevalence of hypertension also depends on sex and age. The prevalence of elevated values (less than or equal to 160/95 mm Hg) identified by measurement, standardized for sex, age and nationality, is 11.6%; if the known, treated hypertensives are included the prevalence is 14.2%. 55% of the hypertensives knew of their condition, 39% were under medical treatment and only 20% were well controlled (greater than 160/95 mm Hg). There were considerable differences between the two region; fewer of the hypertensives were known and fewer were under control in the French-speaking towns.

Adolescent↗
PubMed1979

[Pharmacology of heparin].

After introductory notes on the history of heparin research the chemistry of this mucopolysaccharide is described. It is shown that the chemistry of heparin cannot be exactly described by one chemical formula because heparin represents a family of compounds with different chain-length. Molecular features responsible for the high structural specificity of anticoagulant activity are described. The present status of knowledge on the mechanism of the anticoagulant action of heparin is described in detail. It is shown that basic mechanism is the acceleration of the interaction of antithrombin III with the clotting factors IXa, Xa, XIa, XIIa, and thrombin which are known to be serine proteases. The effects of heparin of platelet function, lipid composition of blood, and on fibrinolysis reflect its complex influence on hemostasis. After a description of side effects and toxicity clinically relevant data on its pharmacocinetics are given.

Animals↗
PubMed1979

[Experimental therapy of disseminated intravascular coagulation by streptokinase administration].

Disseminated intravascular coagulation was induced in dogs by infusion of tissue thrombokinase. Its course was followed by coagulation tests, determination of the rate of microthrombosis, and measurement of organ functions and oxygen consumption. The therapeutic result of streptokinase administration at an early stage of pathological changes is demonstrated by improvement of the disturbed organ functions and oxygen supply as well as by the decrease in plasma-haemoglobin level. When streptokinase was administered at an advanced stage of organ damages, they remained irreversible, although repatency of the microvasculature had been reached.

Animals↗